A technique of using cells isolated from a tissue in testing or examination is an essential method in the biotechnology-related fields. It is widely used in diagnosing a disease or pathological condition, searching for a new drug and evaluating the efficacy of a drug, or in animal inspection, plant inspection, testing for environmental pollutants, and so on. Thus, cells and the like used in the biotechnology field have been greatly diversified.
The isolated cells are sometimes used immediately for testing, but in many cases, the cells are cultured in a culture dish or a test tube. Various examinations are carried out using the cultured cells. Cell lines in culture for use in cell culture tests are required to show drug susceptibility and toxic reaction that are similar to those obtained in a test performed in a living body, that is, a so-called in vivo test. In short, it is necessary to be able to construct an intercellular network regularly arranged on the surface of a cell culture chamber. The intercellular network herein described refers to a state where cells can be connected with each other and interact with each other, a form in which cells are accumulated to form a cell mass, or a form in which cells are formed in a net shape. Furthermore, the cell lines in culture for use in cell culture tests are extremely expensive, so an improvement in survival rate and proliferation rate of cells is desired.
The cell culture tests measure the effect of a drug or the like to be evaluated, by changing its amount, concentration, and the like under the same conditions. For this reason, it is necessary that the cell culture chambers be identical in material, shape, and the like. As the cell culture chambers, a petri dish made of plastic, a petri dish made of glass, a glass plate fixed into a chamber, a well plate, and the like are generally used. Examples of the well plate include 6-well, 12-well, 48-well, and 96-well plates or petri dishes. In general, these plates have substantially the same overall size. As the number of wells increases, the size of a single well becomes smaller. A single well corresponds to a single culture dish. With the recent trend toward miniaturization, a 384-well plate having a number of culture dishes with a small diameter has also come to be used. Bottom surfaces of these culture dishes have a flat plate shape, and each of the bottom surfaces is used as a culture surface.
However, the use of the conventional cell culture chamber for culturing tissue cells causes the cells to be thinned into a form with no orientation. Additionally, the cells are randomly arranged on the surface of the cell culture chamber, so intercellular networks cross each other in a complicated manner. This causes a problem of being incapable of reproducing cell functions in vivo.
As methods for solving the above-mentioned problem and culturing cells in three dimensions, there are disclosed a method for culturing cells utilizing a cell culture chamber having a size on the order of several hundreds of μm (see Patent Document 1), a method for culturing cells utilizing micropatterns including a cell placement section and a flow channel (see Patent Document 2), and the like.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-154027
[Patent Document 2] Japanese Unexamined Patent Application Publication No. 2006-191809